1. Field of the Invention
The present invention relates to an image reading method and apparatus, and particularly to an image reading method and apparatus in which preliminary reading of an image is carried out, and based on the results of the preliminary reading, a reading condition for the main reading of the image is determined, and further, the main reading for the image is carried out under the determined reading condition.
2. Description of the Related Art
There has conventionally been known an image processing system in which a film image recorded on a photographic film is read by an image reading apparatus having a reading sensor such as a CCD, and image data obtained by the reading of the film image is subjected to image processing including various types of correction and the like, and thereafter, an image is recorded onto a recording material or shown on a display.
Further, as the film image, there exist images which have various densities ranging from low density to high density. Accordingly, in order to obtain a recorded or a displayed image having a desired image quality, the image reading apparatus carried out a preliminary reading of a film image (so-called pre-scan), determines a reading condition corresponding to a density of the film image (for example, the amount of light irradiated on the film image, the charge accumulation time of a CCD, or the like), and further, reads the film image under the determined reading condition (so-called fine scan).
When a scanner having a unidimensional reading sensor such as a line CCD is used as the reading means of an image reading apparatus to read film images, reading of a film image, i.e., pre-scan and fine scan, is carried out while a photographic film is being conveyed in a direction perpendicular to the optical axis of the optical system of the scanner at a predetermined speed.
Example of the photographic film to be read by the image reading apparatus are 135-size films, 240-size films, Brownie-size films, and the like. Among these films, 240-size films (which will be hereinafter referred to as APS films) have a magnetic layer formed thereon, and data which expresses photographing conditions (for example, photographing time, whether an electric flash was used, the amount of exposure during photographing, and the like) for each frame is magnetically recorded on the magnetic layer at the time of photographing. The magnetically recorded data which is magnetically recorded on the magnetic layer is necessary for calculation of the reading condition for fine scan and of the processing condition for image processing of the image data obtained by the fine scan.
Accordingly, when a film image recorded on the APS film is read, reading of the magnetically recorded data which is magnetically recorded on the magnetic layer must be carried out in addition to pre-scan and fine scan, and thus, one roll of APS film must be conveyed at least three times. Accordingly, there exists a drawback in that much time is required for reading of the film image and the processing capacity of the apparatus thereby deteriorates.
Further, the APS film set in the scanner is conveyed in a state of constantly contacting a magnetic head for reading the magnetically recorded data, which magnetic head is disposed close to a film conveying path of a film carrier for conveying the APS film. As described above, in the case of the APS film, the film is conveyed during reading of the film image, and therefore, wear of the magnetic head occurs at an early stage and the life duration of the magnetic head is shortened. There also exists a drawback in that the APS film conveyed in the state of contacting the magnetic head is apt to be damaged.
In view of the above-described circumstances, it is an object of the present invention to provide an image reading method and apparatus which can reduce the time required for reading of a film image and can reduce wear of a magnetic head for reading magnetically recorded data and damage to a film.
When a film image is read by a scanner having a line CCD sensor or the like, a film conveying speed suitable for pre-scan is, for example, 150 to 250 mm/second and a film conveying speed suitable for fine scan is, for example, 36 mm/ second. Further, it is desired that a film be conveyed at a speed of 100 mm/second or more for stable reading of magnetically recorded data from the magnetic layer of the APS film.
The present inventors achieved the present invention by having come to the conclusion that, in consideration of the film conveying speeds suitable for pre-scan, reading of magnetically recorded data, and fine scan, pre-scan and reading of magnetically recorded data can be effected concurrently at the same conveying speed (for example, 150 to 200 mm/second), and preliminary reading of a film image and reading of magnetically recorded data can be effected concurrently during one film conveying operation, so as to reduce the number of film conveying operations.
According to the first aspect of the present invention, there is provided an image reading apparatus in which preliminary reading is carried out for a film image recorded on an elongated photographic film, and a main reading condition for main reading of the film image is determined based on results of the preliminary reading, and main reading of the film image is carried out under the main reading condition, comprising reading device which reads the film image recorded on the photographic film, magnetically recorded data reading device which reads first magnetically recorded data which is magnetically recorded on a magnetic recording layer of the photographic film, conveying device which conveys the photographic film and control device for controlling the reading device to carry out the preliminary reading of each of film images recorded on the photographic film while controlling the conveying device to convey the photographic film in a predetermined direction, and for controlling the magnetically recorded data reading device to read the first magnetically recorded date concurrently with the preliminary reading of the film images by the reading device.
According to the second aspect of the present invention, there is provided an image reading apparatus in which the film images sequentially recorded on the elongated photographic film are read by the scanner using line image sensor.
According to each of the first and second aspects of the present invention, the preliminary reading of a film image and the reading of magnetically recorded data are effected concurrently during one film conveying operation, and therefore, the number of times the film must be conveyed in order to read of the film image can be reduced and the time required for reading of the film image can be shortened. Further, wear of a magnetic head for reading magnetically recorded data and damage to the film, which are caused by the conveying of the film, can be lessened.